Reizer J, Hoischen C, Titgemeyer F, Rivolta C, Rabus R, Stülke J, Karamata D, Saier M H, Hillen W
Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA.
Mol Microbiol. 1998 Mar;27(6):1157-69. doi: 10.1046/j.1365-2958.1998.00747.x.
HPr(Ser) kinase is the sensor in a multicomponent phosphorelay system that controls catabolite repression, sugar transport and carbon metabolism in gram-positive bacteria. Unlike most other protein kinases, it recognizes the tertiary structure in its target protein, HPr, a phosphocarrier protein of the bacterial phosphotransferase system and a transcriptional cofactor controlling the phenomenon of catabolite repression. We have identified the gene (ptsK) encoding this serine/threonine protein kinase and characterized the purified protein product. Orthologues of PtsK have been identified only in bacteria. These proteins constitute a novel family unrelated to other previously characterized protein phosphorylating enzymes. The Bacillus subtilis kinase is shown to be allosterically activated by metabolites such as fructose 1,6-bisphosphate and inhibited by inorganic phosphate. In contrast to wild-type B. subtilis, the ptsK mutant is insensitive to transcriptional regulation by catabolite repression. The reported results advance our understanding of phosphorylation-dependent carbon control mechanisms in Gram-positive bacteria.
HPr（丝氨酸）激酶是多组分磷酸化中继系统中的传感器，该系统控制革兰氏阳性菌中的分解代谢物阻遏、糖转运和碳代谢。与大多数其他蛋白激酶不同，它识别其靶蛋白HPr中的三级结构，HPr是细菌磷酸转移酶系统的磷酸载体蛋白，也是控制分解代谢物阻遏现象的转录辅因子。我们已经鉴定出编码这种丝氨酸/苏氨酸蛋白激酶的基因（ptsK），并对纯化的蛋白产物进行了表征。仅在细菌中鉴定出了PtsK的直系同源物。这些蛋白质构成了一个与其他先前表征的蛋白磷酸化酶无关的新家族。已证明枯草芽孢杆菌激酶被诸如1,6-二磷酸果糖等代谢物变构激活，并被无机磷酸盐抑制。与野生型枯草芽孢杆菌相比，ptsK突变体对分解代谢物阻遏的转录调控不敏感。所报道的结果增进了我们对革兰氏阳性菌中磷酸化依赖性碳控制机制的理解。
